German Patent DE-OS 2,031,085 discloses an electronic circuit which is enclosed in a generally flat body such as an identification card or credit card to be identified by means of an identifying device. Power is supplied to the electronic circuit in the flat body by means of a radiation source in the identifying device and a photocell in the flat body to be identified.
It is an object of the present invention to provide a card to be identified by an identifying device, which card is capable of optically receiving information from the identifying device and is capable of optically transmitting information to the identifying device.